The 24-hour labour action has deprived the country of train and ferry services and will sideline dozens of flights.

Hospitals will operate on emergency footing, gas stations will remain closed and taxis have been pulled off the streets.

Lawyers and farmers are also participating in the walkout.

The general strike, the third in as many months, is directed against government plans to lower the maximum pension to 2,300 euros (USD 2,500) a month from 2,700 euros currently and introduce a new minimum guaranteed basic pension of 384 euros.

The leftist administration of Prime Minister Alexis Tsipras also wants to merge pension funds and increase social security contributions by both employers and staff.

The farmers have formed protest hubs at dozens of locations on Greece's national highways, intermittently blocking traffic with tractors over the past two weeks.